Pneumatic automobile spring



Jan. 19 ,1926. 1,569,850

E.- E. COTHRAN PNEUMATIC 'AUTOMOBILE SPRING Filed Sept. 14. 1921 FIGURE a FIGURE Z 4 INVENTQR Patented Jan. 19, 1926.

UNITED STATES PATENT OFFICE.

` EDWARD EVERETT COTHRAN, OF lWRIGHT, UALIORNA;

` `PNLJUMA'IEIC AUTOMOBILE SPRING. u

Application filed September 14, 1921. Serial No. 500,538.

To all whom it may concem:

Be it known that I, EDWARD EVERETT Cori-IRAN, a citizen of the United States, residing at VVI-ight, in thecounty of Santa Clara and State of California, have invented a new and useful PneumatieAutomobile Spring, of which the following is a speci i fication.

I `frame of the chassis and axles of the automobile; second, to reduce the vibrations and eliminate the jolts and shocks of the automobile under all working conditions; third, to render pneumatic tires upon pleasure cars unnecessary and permit in their stead the use 'of solid rubber and metallc` tires; fourth, to allow chains or other non-skidding devices to be used upon the` wheels without causing the automobile to ride hai-der, and fifth, to increase the economy,`

comfort and safety of such machine.

I attain these objects by the mechanism illustrated in the accompanying drawing, in which i r u Figure `1 is a View which, lookingforward from the right rear aXle, shows such pneumatic spring as it appears in its proper connecton with the axle and chassis frlame of the automobila, together with the Outline of a tire; Fig. 2 is a separate View of one of the two similar compressed air chambers,

y outer cases, lugs and air-valves that con- V stitute the purely pneumatic elements of said spring; and Fig. 3 is a View of one of i the similar ball-bearings and their annular containing grooves with the cross-section of 'one of the bolts against which suid ballbearings work in said mechanism; four such bearings being required for each pneumatic spring. 1 Similar numerals refer to similar parts throughout the several views. i

u In Figure 1,` 1 is the stationaryhousing. of the axle and which for convenience is;

herenafter designated asthe axl'e of an g automobile, orsimply as the axle, 2 isthe `frame of the chassis and 3 are similar round steel bolts Vertically set and immovably fixed in the frame of the chassis and extending downward, one in front, the other behind the axle, 4 is a concave metallic plate, shaped somewhat like the upper half of an ellipse, with a round hole at each end through which said bolts pass and extend and at which points said plate is rigidly aiiixed to said bolts by nuts or other suitable means; 5 is a netallic plate, shaped some- What like the lower half of "an ellipse with a square depression therein immediately next the axle to which axle, said plate at the bottom of said square depression in said plate, is rigidly afiixed by welding or bolting said plate to the top of said axle; said plate 5 having at each end ball bearings through which bearings said bolts respectively pass and extend downward in front and behind the axle; 6, 6, 6 and 6 are ballbearings; 7 is a metallic plate, shaped somewhat like the upper half of an ellipse, with a square elevation therein immediately next the axle to which axle, said plate at the top of said square elevation in said plate,- is rigidly aflixed by welding or bolting said plate to the under surface of said axle; said plate 7 having at each end ball-bearings through which bearings said bolts respectively pass and extend downward in front and behind the aXle; 8, 8, 8 and 8 are oil 01' grease cups enclosing said bearngs for the purpose of lubrication; 9 is a metallic plate, shaped sonewhat like the lower half of an ellipse, with a hole at each end through which said bolts respectively pass and at which points said plate is rigidly aflixed by nuts or other suitable means; 10 and 10 are seamless rubber chambers, elliptical in shape, 11 and 11 are seamless outer cases made of layers of cloth fabric covered with y with the exterior surfaces of said respective outer cases, one of the said lugs being dei signed to tightly fit in the square depression injplate 5, the other of said lugs being designed` to tightly fit in the square elevation in plate 7; the said lugs 12 and 12, being vulcanized to therespective outer cases 11 and 11, and fitting tightly in the square depression in plate 5 and in the square elevation in plate 7 respectively, are for the purpose of preventing the said outer cases from turning or shifting in position during the operation of the automobile and of always keeping the air-valves 13 and 13 in the places shown in Fig. 1. 13 and 13 are air-valves seated in said respective rubber chambers and extending through said outer cases to the open air whereby said rubher ehanbers are inflated with conpressed air; said plates l and 5 snugly embrace, so as to securely hold in position, part of the exterior surface of one of said outer cases containing said rubber chambers, while the square depression in plate 5 tightly fits the square lug vulcanized to said outer case; said plates T and 9 snugly embrace, so as to securely hold in position, part of the exterior surface of another of said outer cases containing said rubber chambers, while the square elevation in plate 7 tightly fits the square lug vulcanized to said outer case.

The plates t and 9, being rigidly aflixed to the bolts 3 and 3, the latter rigidly afixed to the frame of the chassis 2, can only move up and down with the ehassis; and the plates 5 and 7, being rigidly afiixed to the axle, and having ball-bearings, are free to move up and down with every upward and downward motion of the axle and wheels of the automobile, while said outer cases and rubber airchamhers are synchronously and elastically expanded or compressed.

The ruhher chanbers 10 and 10 and their outer cases 11 and 11 must always be so that, under their working air pressure, they possess greater external surface dinensions than the internal surface dimensione of said metallic plates.

Thus, when 10 and 10 are inflated with compressed air, the plates 4: and 5 or the plates T and 9 cannot come in physical contact but are kept well apart under all conditions.

In the average pleasure automobile, the upper and lower metallic plates may einbrace two-thirds of the surface of an outer case, leaving one-third the surface around the center of the elliptcal surface of the case exposed to the air and capable of yielding and expanding elastically when the automobile is subjecte'd to vibration, jolts and shocks.

Preferably, however, the plates should be so curved that the elliptical outer cases and air ehambers, when under the pressure of normal working inflation, rest against the interier surface of the upper and lower plates for only one-half the distance from the vertices at the axis ininor to the principal vertices at the axis major of the said ellipse. y

The plates thus securely hold in position said outer cases and air chamhers and still permt them to yield, compress and expand elastically under inereased and varying weights or the sudden pressure produced by vbratons, j olts and shocks.

The edges of the plates must also be made with a small outward curve to prevent the possibility of abrasion of the outer cases and air chanhers when the automobile is subjected to great and unusual shocks. 'While I prefer outer cases and air chambcrs ell'pti -al in shape with correspondingly forned plates, of the above relative dinensions, I do not wish the invention to be confined to such shapes and dinensions for the reason that it will work with spherical,cylindrical, square and other shapes and with different relative di'nensions.

The foregoing description of the parts illustrated in Fig. 1, constitutes what may be termed one pneumatc automobile spring.

Four such springs are necessary, and are arranged at substantially the same places on the two axles used 'for the existing steel springs of the automobile.

In Fig. 2, 10 is an elliptically shaped and seanless chamber made of ruhber in which an air-valve, 13, is seated; 11 is also an elliptically shaped and seamless outer case, made of layers of cloth fabric covered with ruhber and vulcanized into one piece, conpactly surrounding but not integral with said chamber, 10, and through which ease said airvalve extends to the open air; the said valve being used to inflate said chamber with com pressed air and being substantally the same type as the valve now enployed for inllating autonobile pneumatic tires; 1'2 is a square solid rubber lug vulcanized to, and made integral with said outer case, 11.

In Fig. 3, the balls of one ball-hearing are shown as they surround and work against the bolt, 3, the latter in cross-section; 14 shows an annular groove or collar in which the balls are contained and move as they work against the round surface of said bolt as bearings.

Said annular groove, containing the balls, is welded or by other suitable means alixed to the repspective plates 5 and T, shown in Fig. 1. An air ehamber and outer case, such as those described and illustratecl in Figs. l and 2, when six to seven inches in length by five to six inches in width, aiford a larger pneumatc surface to sustain the weight of the automobile than the ordinary pneunatic tire, since only a small fraction of the tii-e at'any given moment sustains such weight while most of the surface of the tire merely serves the function of a pneunatic wheel in the air.

In the invention, also, only the weight "over the axles is sustained by the pneumatic springs. i

As the plates, an' chambers and outer cases below the axles sustan simply the pressure and absorb the shocks of upward jolts and motions or those motions that are swiftly compounded of all the vibrations of the automobile, they may be constructed, when desired, of smaller dimensions, still i keeping them of equal length with the plates,

i the like indespensable use of chains does not prodnce inequalities of surface at the very points where the principles of resiliency are at work. While the invention is designed to eliminate steel sprngs and all types of Shock absorbers, it is likewise thought that its use will displace pneunatic tires as unnecessarily costly and unsafe as compared with solid rubber or me-tallic tires.

The two bolts, 3 and 3, being rigidly affixed to the frame of the automoble and also to the plates 4 and 9, and being set one in front, the other behind the axle, and the plates 5 and 7 being rigidly afiixed to the axle, one above, the other below it, and such plates 5 and 7 working freely up and down with the axle through said balLbearings and grease cups, it is obvious that 'ricton is very small and that forward, back- Ward or sideway lurchings of the chassis are prevented, thus giving the described pneumatic springs a maximum of strength and resiliency. V

The weight sustained by said air chambers and onter cases being less than that sustained by the tire for a given automobilc, the air pressures for carrying capacities for each pneumatic spring is less than the air pressures for carrying capacities for each pneumatic tire per square inch of active pneumatic surface.

Moreover, the material in said air chambers and outer cases is not, as in the tire, exposed to the wear and tear of direct contact with the road; but, on the contrary, the metallic plates, smoothly polished and al ways presenting a uniform surface to said outer cases and lugs, these are practically free from puncture or blow-out.

The amount of rubber and fabric employed in the Construction of the eight chambers and cases for the pneumatiesprings of an automobile is manfestly far less than what is required for the four tires now in' use.

The econom of the mechanism may, hence, be readil y perceived.

Having described and illustrated my invention, I claim:

1. In a pneumatic Spring of the character described and in combination, a vehicle axle a chassis frame member, a pair of spaced vertcally disposed elongated bolts fixed to the frame member and extending downwardly on opposite sides of the aXle; a seni-elliptically shaped metal plate, having a square depression therein, fixed to the top of said aXle; a seni-elliptically shaped metal plate, having a square elevation therein, fixed to the bottom of said axle; opposite sides of each of said plates being fixed to said bolts with collars; a pneumatic elliptioally shaped bag with a square and solid rubber lug vulcanized to the bottom of said bag seated in said square depression in said plate fixed to the top of said axle; a pneumatic elliptically shaped bag With a square and solid rubber lug vulcanized to the top of said latter bag seated in said square elevation in said plate fixed to the bottom of said axle; said plates having a slding connection around said bolts through lnbricated ballbearings set in said collars integral with and upon opposite sides of each of said plates; a semi-elliptically shaped metal plate fixed to said bolts on opposite sides of said axle and cove-ring said bag above said axle; a semi-elliptically shaped metal plate fixed to said bolts on opposite sides of said axle and supporting said bag below said axle.

2. In a pneumatc spring of the character p described and in combination, a vehicle axle, a chassis frame member, a pair of spaced vertically disposed elongated bolts fixed to the frame member and extendngly down wardly on opposite sides of the axle; a semielliptically shaped metal plate, one welded to the top of said axle, another welded to the bottom of said a de, opposite sides of each of said plates being fixed to said bolts; said plates having a sliding connection on said bolts; said sliding connection compris ing a collar containing ball-bearings provded on opposite sides of each of said plates and through which ball-bearngs said bolts pass; an elliptically shaped pneumatic bag seated in each of said plates; a solid rubber cushion incorporated in each of said seats and presented between the axle and each oi said pneumatic bags; a semi-elliptically shaped metal plate covering the pnenmatic bag above the aXle, and a semi-elliptioally shaped metal plate supporting the pneumatc bag seated below the axle.

EDWARD EVERETT COTHRAN. 

